1. Field of the Invention
The present invention relates to, for example, a device configured to convey a conveyance object such as a piece of paper to a target position.
2. Description of the Related Art
A conveyance device configured to convey a conveyance object such as a piece of paper or a piece of paper currency to a target position is used in an image forming apparatus such as a printer or another apparatus.
Japanese Laid-open Patent Publication No. 2007-316608 discloses an image forming apparatus including a paper conveyance device. An objective of the image forming apparatus is to prevent the deterioration of the positional deviation correction or the phase adjustment accuracy while a plurality of latent image carriers drives at different linear velocities, by forming an image for detecting a positional deviation or an image for detecting a speed variation. Thus, the image forming apparatus forms an image for detecting a positional deviation or an image for detecting a speed variation while driving the latent image carriers at the same speed.
Japanese Laid-open Patent Publication No. 2012-177971 discloses a paper sheet processing apparatus configured to convey, for example, a sheet of paper current in a ticket vending machine. An objective of the paper sheet processing apparatus is to enable a reciprocating conveyance unit conveying a sheet of paper to appropriately stop at the target position even when the variation in the load or temperature of the motor changes, in response to the number of sheets of paper, an appropriate value to be set as the target value used for the control. Thus, the paper sheet processing apparatus corrects the target value every time when the motion of the reciprocating conveyance unit is controlled in such a way as to eliminate the positional deviation between the stop position and the target stop position using the predetermined reference detection position.
In order to improve the stop position accuracy in the control of the motor driving a conveyance roller configured to convey a print medium, Japanese Laid-open Patent Publication No. 2009-73181 discloses a technique to terminate a speed feedback control and perform a position feedback control when the number of remaining pulses to the target stop position becomes equal to or less than a threshold in the deceleration area.
To appropriately convey and stop a conveyance object such as a piece of paper at the target position, it is necessary to accurately control the revolution speed of the motor that drives a conveyer, for example, a roller. Japanese Laid-open Patent Publication No. 2012-177971 corrects the target value of the stop position of the reciprocating conveyance unit using the predetermined reference detection position. However, Japanese Laid-open Patent Publication 2012-177971 does not improve the controllability on the revolution speed of the motor. There is a problem in Japanese Laid-open Patent Publication No. 2009-73181 in that the period between the start of the position feedback control and the time when the conveyance object reaches the target stop position varies depending on the load of the motor because the position feedback control is performed based on the number of remaining pulses.
In light of the foregoing, an object of the present invention is to improve the controllability on the motor.